Rustic whole wheat flour will suck up more moisture than lighter-colored flour. Basically you just have to know what texture you are after. I think starting wetter and needing more flour is better than trying to get more water into a too-dry mix.
Of course, the final result might still be a little strange.
I see that once in a while a recipe will call for white whole wheat flour. Is there any cooking difference between that and just regular whole wheat flour ?
I don't want to buy it for one recipe if my other will work the same.